Substitute I with N and print

    

while($_= <DATA>){
    print if s/I/N/;
}
__DATA__
    S
    B
    I
    N
    J
    K

1.	Options for the substitution operator.
2.	Replace pattern
3.	Replace pattern with ()
4.	Substitute N with J
5.	Substitute every T with M
6.	Substitute first T with an M
7.	Substitute first occurrence of "blue" with "red"
8.	Substitute tom with Mary
9.	Substitution Example
10.	Substitution Modifiers
11.	Using substitutions to clean up input data.
12.	Capitalize all sentences
13.	Using Patterns with Substitutions
14.	Changing substitution delimiters
15.	Increase salary with pattern match
16.	Evaluate replacement
17.	Alternation: /John\|Karen\|Steve/ will match a line containing John or Karen or Steve.
18.	Options for the S Operator
19.	Ignore case, global substitution

Substitute I with N and print : substitution « Regular Expression « Perl